title: Host defenses in experimental scrub typhus: inflammatory response of congenic C3H mice differing at the Ric gene.
abstract: Two strains of C3H mice differed in their susceptibility to lethal infection with Rickettsia tsutsugamushi strain Gilliam. Adult C3H/RV mice were markedly more resistant to lethal infection than C3H/HeDub mice, and both were histocompatible as assessed by mixed-lymphocyte cultures and graft-versus-host responses. The inflammatory response of susceptible C3H/HeDub mice to intraperitoneal infection was evident approximately 5 days postinfection, and the magnitude of the cellular influx increased until death of the animal. The inflammation consisted of an early polymorphonuclear leukocyte response, followed by a mononuclear cell influx which persisted until death of the animal. The C3H/RV mice evidenced similar kinetics of cell influx, but the inflammatory response was significantly reduced in magnitude, and the response of C3H/RV animals to Gilliam was predominantly mononuclear in nature, with little influx of polymorphonuclear leukocytes into the peritoneal cavity. C3H/RV mice were rendered susceptible to Gilliam infection by induction of a nonspecific inflammation with thioglycolate if given 3 days after infection. Conversely, treatment of C3H/HeDub mice with indomethacin, an anti-inflammatory agent, prolonged survival after infection with Gilliam. The results of this study indicate that genetic resistance to Gilliam is not due simply to a greater host response to infection or, conversely, that susceptibility is due to a host response quantitatively lacking in a cellular component necessary for antirickettsial immunity.
mesh_terms: D000818:Animals; D005260:Female; D007111:Immunity, Cellular / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects; D007213:Indomethacin / Q000494:pharmacology; D007249:Inflammation; D051379:Mice; D008809:Mice, Inbred C3H / Q000235:genetics / Q000276:immunology*; D012285:Orientia tsutsugamushi / Q000276:immunology; D012612:Scrub Typhus / Q000235:genetics / Q000276:immunology*; D013864:Thioglycolates / Q000494:pharmacology
chemical_list: D013864:Thioglycolates; D007213:Indomethacin